Details about high Rise Buildings Structural Systems

Requirement for high-rise buildings: The High rise buildings are gaining popularity in recent times for the following purposes -

• Shortage of land.
• High demand for business and residential space.
• Economic Growth.
• Technological Progression.

• Inventions in Structural Systems.
• Aspiration for aesthetics in urban settings.
• Cultural significance and prestige.
• Human Desire to build higher.

Now-a-days, the high rise buildings are constructed with steel-framed construction, reinforced concrete construction and steel- framed reinforced concrete construction. Besides, hybrid systems are developed during this time. These systems apply in excess of one type structural system in a building.

Structural Concern

Fighting gravity

• The weight of the building is supported with a wide array of vertical columns.
• Each floor is supported with horizontal steel girders driving among vertical columns.
• Curtain wall with steel and concrete are affixed to the outside.

Wind Resistance

• Building longer than 10 stories would normally need extra steel for lateral system.

• The elementary process for managing horizontal sway is to just brighten the structure. At the position, where the horizontal girders are connected to the vertical column, the construction crew bolt, welds them on the top and bottom as well as the side. It will facilitate the complete steel super structure to move more as one unit, like a pole, instead of a flexible skeleton.

• The impact of wind is also reduced by aerodynamic shaping of the building. Wind tunnel testing provides perfect loading for overall lateral system design and cladding design, and indicates motion perception and pedestrian level effects.



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Published By
Rajib Dey
www.constructioncost.co
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Some useful tips to eliminate the deficiencies of the reinforced concrete shear walls

Reinforced concrete shear walls are considered as perfect structural systems for a long time which offer both lateral resistance and drift control in RC buildings.

However these aging shear walls were normally designed for combined actions against gravity loads and wind loading. Seismic loading and design were not taken into consideration for day to day mid-height building structures.

There are lots of shortcomings in design and detailing of these shear walls and because of these, the shear walls become susceptible to seismic hazard.

General shortcomings of Thin Reinforced Concrete Shear Walls :-

The following shortcomings are mostly found in several existing buildings:

• Deficient wall thickness containing only one curtain of distributed horizontal and vertical reinforcement;
• Deficient lap splice lengths of the longitudinal reinforcement;
• lap splices are situated in the zones of potential plastic hinging;
• Insufficient confinement of the end regions of the walls;
• Deficiency in controlling the buckling of the flexural reinforcement;
• Inadequate amounts and defectively detailed transverse (shear) reinforcement.

Points to be followed for improvements:

To improve the condition of these defective walls, various repair and retrofit schemes should be undertaken.

The details of these schemes are given below:

Carbon-Fiber Reinforced Polymer (CFRP) wraps:

Under this method, the shear wall is covered with a layer of CFRP sheet. This layer makes the confinement better around the boundary elements to some extent. As this confinement effect is nominal, it enhances the ductility of the section, and prevents brittle failure of lap splices.

Fibre-Reinforced Self Consolidating Concrete Jacketing

A combination of steel fibers and reinforcement are applied to enhance the flexural strength of concrete section, and the simultaneously, increases the ductility of the wall to the new plastic hinge location.



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Published By
Rajib Dey
www.constructioncost.co
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